From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5A8BEC433F5 for ; Thu, 16 Dec 2021 16:54:51 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.248129.427964 (Exim 4.92) (envelope-from ) id 1mxu1Y-0001YH-MJ; Thu, 16 Dec 2021 16:54:32 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 248129.427964; Thu, 16 Dec 2021 16:54:32 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mxu1Y-0001YA-Ig; Thu, 16 Dec 2021 16:54:32 +0000 Received: by outflank-mailman (input) for mailman id 248129; Thu, 16 Dec 2021 16:54:31 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mxu1X-0001Y4-If for xen-devel@lists.xenproject.org; Thu, 16 Dec 2021 16:54:31 +0000 Received: from ppsw-43.csi.cam.ac.uk (ppsw-43.csi.cam.ac.uk [131.111.8.143]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id d5632107-5e90-11ec-9e60-abaf8a552007; Thu, 16 Dec 2021 17:54:30 +0100 (CET) Received: from hades.srcf.societies.cam.ac.uk ([131.111.179.67]:47098) by ppsw-43.csi.cam.ac.uk (ppsw.cam.ac.uk [131.111.8.139]:25) with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) id 1mxu1U-000vc3-pF (Exim 4.95) (return-path ); Thu, 16 Dec 2021 16:54:28 +0000 Received: from [192.168.1.10] (host-92-12-61-86.as13285.net [92.12.61.86]) (Authenticated sender: amc96) by hades.srcf.societies.cam.ac.uk (Postfix) with ESMTPSA id B236A1FB36; Thu, 16 Dec 2021 16:54:28 +0000 (GMT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: d5632107-5e90-11ec-9e60-abaf8a552007 X-Cam-AntiVirus: no malware found X-Cam-ScannerInfo: https://help.uis.cam.ac.uk/email-scanner-virus Message-ID: Date: Thu, 16 Dec 2021 16:54:28 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH v2 1/4] x86/cpuid: Split dom0 handling out of init_domain_cpuid_policy() Content-Language: en-GB To: Jan Beulich , Andrew Cooper Cc: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , Xen-devel References: <20211215222115.6829-1-andrew.cooper3@citrix.com> <20211215222115.6829-2-andrew.cooper3@citrix.com> <8e648c7b-33a6-642c-e4ff-78f17a35dbe3@srcf.net> From: Andrew Cooper In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 16/12/2021 16:51, Jan Beulich wrote: > On 16.12.2021 17:41, Andrew Cooper wrote: >> On 16/12/2021 16:38, Jan Beulich wrote: >>> On 15.12.2021 23:21, Andrew Cooper wrote: >>>> To implement dom0-cpuid= support, the special cases would need extending. >>>> However there is already a problem with late hwdom where the special cases >>>> override toolstack settings, which is unintended and poor behaviour. >>>> >>>> Introduce a new init_dom0_cpuid_policy() for the purpose, moving the ITSC and >>>> ARCH_CAPS logic. The is_hardware_domain() can be dropped, and for now there >>>> is no need to rerun recalculate_cpuid_policy(); this is a relatively expensive >>>> operation, and will become more-so over time. >>> Would you mind leaving it there in a commented out form, hinting at when >>> it may need re-enabling? >> Leave what?  The recalculate_cpuid_policy()?  That comes back in later >> in the series. > I've meanwhile spotted it, yes. Let's hope its conditional invocation > there makes clear enough that with certain other changes it may also > be needed. In reality, I expect ITSC never to need a recalc, and ARCH_CAPS is going to turn into not-a-special-case just as soon as I can possibly make it happen. ~Andrew